Make change_priority API consistent

src/double_priority_queue/mod.rs

@@ -472,17 +472,25 @@ where
     }
 
     /// Change the priority of an Item using the provided function.
+    /// Return a boolean value where `true` means the item was in the queue and update was successful
+    ///
+    /// The argument `item` is only used for lookup, and is not used to overwrite the item's data
+    /// in the priority queue.
+    ///
     /// The item is found in **O(1)** thanks to the hash table.
     /// The operation is performed in **O(log(N))** time (worst case).
-    pub fn change_priority_by<Q: ?Sized, F>(&mut self, item: &Q, priority_setter: F)
+    pub fn change_priority_by<Q: ?Sized, F>(&mut self, item: &Q, priority_setter: F) -> bool
     where
         I: Borrow<Q>,
         Q: Eq + Hash,
         F: FnOnce(&mut P),
     {
-        if let Some(pos) = self.store.change_priority_by(item, priority_setter) {
-            self.up_heapify(pos);
-        }
+        self.store
+            .change_priority_by(item, priority_setter)
+            .map(|pos| {
+                self.up_heapify(pos);
+            })
+            .is_some()
     }
 
     /// Get the priority of an item, or `None`, if the item is not in the queue

src/priority_queue/mod.rs

@@ -406,17 +406,25 @@ where
     }
 
     /// Change the priority of an Item using the provided function.
+    /// Return a boolean value where `true` means the item was in the queue and update was successful
+    ///
+    /// The argument `item` is only used for lookup, and is not used to overwrite the item's data
+    /// in the priority queue.
+    ///
     /// The item is found in **O(1)** thanks to the hash table.
     /// The operation is performed in **O(log(N))** time (worst case).
-    pub fn change_priority_by<Q: ?Sized, F>(&mut self, item: &Q, priority_setter: F)
+    pub fn change_priority_by<Q: ?Sized, F>(&mut self, item: &Q, priority_setter: F) -> bool
     where
         I: Borrow<Q>,
         Q: Eq + Hash,
         F: FnOnce(&mut P),
     {
-        if let Some(pos) = self.store.change_priority_by(item, priority_setter) {
-            self.up_heapify(pos);
-        }
+        self.store
+            .change_priority_by(item, priority_setter)
+            .map(|pos| {
+                self.up_heapify(pos);
+            })
+            .is_some()
     }
 
     /// Get the priority of an item, or `None`, if the item is not in the queue

tests/double_priority_queue.rs

@@ -259,9 +259,9 @@ mod doublepq_tests {
         let v = vec![("a", 1), ("b", 2), ("f", 7), ("g", 6), ("h", 5)];
         let mut pq: DoublePriorityQueue<_, _> = DoublePriorityQueue::from_iter(v.into_iter());
 
-        pq.change_priority_by("z", |z| *z += 8);
+        assert!(!pq.change_priority_by("z", |z| *z += 8));
 
-        pq.change_priority_by("b", |b| *b += 8);
+        assert!(pq.change_priority_by("b", |b| *b += 8));
         assert_eq!(
             pq.into_descending_sorted_vec().as_slice(),
             &["b", "f", "g", "h", "a"]

tests/priority_queue.rs

@@ -249,7 +249,7 @@ mod pqueue_tests {
         let v = vec![("a", 1), ("b", 2), ("f", 7), ("g", 6), ("h", 5)];
         let mut pq: PriorityQueue<_, _> = PriorityQueue::from_iter(v.into_iter());
 
-        pq.change_priority_by("b", |b| *b += 8);
+        assert!(pq.change_priority_by("b", |b| *b += 8));
         assert_eq!(pq.into_sorted_vec().as_slice(), &["b", "f", "g", "h", "a"]);
     }